Supersensitization of photographic emulsions



S p 1958 J. E. JONES 2,852,385

SUPERSENSITIZATION OF PHOTOGRAPHIC EMULSIONS Filed May 14, 1956 'B I A1 4m ILIQPFFFTWYHQLMHLEIXM llll A 3,3". DIETHYLOXATHIADICARBOCYANINE IODIDE B= 2 p- DI ETHYLAMINOBENZALAMQNOBENZOTHIAZOLE C= 3,3 D lETHYLOXATHIADICARBOCYANIN'E IODIDE PLUS 2 "51' 0| ETHYLAMINOBENZALAMINOBENZOTHIAZOLE 92 0 E /A mm m IIMW MM 300 400 500 V 600 700 A =3,3" D lETHYLOXATHIADICARBOCYANINE IODIDE D 2'2DIETHYLAMINOSTYRYLBENZOTHIAZOLE E 3,3" DIETHYLOXATHIADICARBOCYANINE IODIDE PLUS 2 p DI ETHYL'AMINOSTYRYLBENZOTHIAZOLE 500 600 3,3 DIETHYLOXATHIADICARBOCYANINE IODIDE 2' 4' (P'DIMETHYLAMINOPHENYL) 'l,3 BUTADIENYL] BENZOTHIAZOLE 3,3 DIETHYLOXATHIADICARB'OC YANINE IODIDE PLUS 2" [4" (2' DINETHYLAMINOPHENYL) 1,3 BUTADIENYL] BENZOTHIAZOLE 700 A F s Ill ll Jean Jones United States Patent SUPERSENSITIZATION OF PHOTOGRAPHIC EMULSIONS Jean E. Jones, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application May 14, 1956, Serial No. 584,553

16 Claims. (Cl. 96104) This invention relates to photographic silver halide emulsions useful in color photography and photographic silver halide emulsions containing dicarbocyanine dyes, and as supersensitizers therefor, styryl-type bases.

It is known in the art of making photographic emulsions that certain dyes of the cyanine class alter the sensitivity of photographic emulsions of the gelatino-silver-halide kind, when the dyes are incorporated in the emulsions. It is also known that the sensitization produced by a given dye varies somewhat with the type of emulsion in which the dye is incorporated. Furthermore, the sensitization of a given emulsion by a given dye may be altered by varying the conditions in the emulsion. For example, the sensitization may be increased by increasing the silver ion concentration or decreasing the hydrogen ion concentration (i. e., increasing the alkalinity) or both. Thus, sensitization can be increased by bathingv plates, coated with a spectrally sensitized emulsion, in water or in aqueous solutions of ammonia. Such a process of altering the sensitivity of a sensitized emulsion by increasing the silver ion concentration and/ or by decreasing the hydrogen ion concentration is commonly called hypersensitization. Hypersensitized emulsions have generally poor keeping qualities.

I have now found another means of altering the sensitivity in emulsions containing dicarbocyanine dyes. Since the conditions in the emulsion, i. e., the hydrogen ion and/ or the silver ion concentration undergo little or no i change in my method, I shall designate my method as a kind of supersensitization.

It is, therefore, an object of my invention to provide photographic emulsions containing dicarbocyanine dyes and, as supersensitizers therefor, styryl-type bases. An-

' other object is to provide a process for preparing these supersensitized emulsions. Other objects will become apparent from a consideration of the following description and examples.

The dicarbocyanine dyes which are useful in practicing my invention include those represented by the following general formula:

wherein R and R each represents an alkyl-group (such as methyl, ethyl, B-hydroxyethyl, carboxymethyl, S-carboxyethyl, carbomethoxymethyl, carbethoxymethyl, etc., n

represents a positive integer of from 1 to 2, X represents an acid radical, such as chloride, iodide, bromide, perchlorate, p-toluenesulfonate, benzenesulfonate, ethylsulfate, methylsulfate, etc., Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus conmethylbenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole, S-bromobenzothiazole, d-bromobenzothia- Patented Sept. 16, 1958 thoselenazole series (e. g., a-naphthoselenazole, B-naphthoselenazole, etc.), a heterocyclic nucleus of the benzoxazole series (e. g., benzoxazole, S-hydroxybenzoxazole, 6- hydroxybenzoxazole, S-chlorobenzoxazole, S-methoxybenzoxazole, 6-methoxybenzoxazole, 5- phenylbenzoxazole, 5- bromobenzoxazole, etc.), a heterocyclic nucleus of the naphthoxazole series (e. g., a-naphthoxazole, /3-naph thoxazole, etc.), a heterocyclic nucleus of the Z-quinoline series (e. g., Z-quinoline, 6-methyl-2-quinoline, 7-methyl- 2-quinoline, S-methyl-Z-quinoline, 6-chloro-2-quinoline, 8-chloro-2-quinoline, 4-chloro-2-quinoline, 5-ethoxy-2- quinoline, 6-ethoxy-2-quinoline, 7-ethoxy-2-quinoline, 6- hydroxy-Z-quinoline, 7-hydroxy-2-quinoline, 6-methoxy-2- quinoline, etc.), .a heterocyclic nucleus of the 4-quinoline series (e. g., 4-quinoline, 6-methoxy-4-quinoline, 7-methyl- 4-quinoline, 8-methyl-4-quinoline, etc.), a heterocyclic nucleus of the benzimidazole series (e. g., benzimidazole, S-chlorobenzimidazole, 5,6-di-chlorobenzimidazole, 1,7- trimethylenebenizimidazole, etc.) a heterocyclic nucleus of the 5,6-benz0quinoline series (e. g., 5,6-benzo-2-quinoline, etc.), etc., and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzoxazole series (e. g., such as those defined by Z above), those of the naphthoxazole series (e. g., such as those defined by Z above), those of the benzoselenazole series (e. g., such as those defined by Z above), those of the naphthoselenazole series (e. g., such as those defined by Z above), those of the benzothiazole series (e. g., such as those defined by Z above), those of the naphthothiazole series (e. g., such as those defined by Z above), etc. Other dicarbocyanine dyes can also be employed in my invention.

The styryl-type'bases useful in practicing my invention can advantageously be represented by the following general formulas:

wherein R represents a monocyclic aryl group of the benzene series, such as phenyl, dimethylaminophenyl (o-, m-, or -p), diethylaminophenyl (0 m-, or p-), aminophenyl (o-, m-, or p-), hydroxyphenyl (0-, m-, or p-), chlorophenyl (o-, m-, or -p-), etc., 11 represents a positive integer of from 1 to 2, L represents a nitrogen atom or a methine group, i. e., CR wherein R is a hydrogen atom, a cyano group, an alkoxyl group (methoxyl, ethoxyl, etc., for example), etc., and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus, such as those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the oxazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the selenazole series,-those of the benzoselenazole series, those of the naphthoselenazole series, those of the perinaphtho- 1,3-thiazine series, those of the Z-quinoline series (It is 1),

methods well known to those skilled in the art. For

example, these styryl-type bases can be prepared by condensing a heterocyclic base containing a reactive amino or methyl group with an aromatic aldehyde. Alternatively, they can be prepared by dequaternization of the corresponding styryl dyes, as described in U. S. Patent 2,169,434, issued August 15, 1939. Listed below are representative styryl-type bases of Formulas II or III which can advantageously be employed in my invention.

\ V /C7H5 C 2115 2-p-diethylaminobenzalaminobenzothiazole (J2EE 2-p-diethylaminostyrylbenzothiazole 2-(a:-cyano-p-diethylaminostyryl)benzothiazole 2-[4- p-dimethylamlnophenyl) -1,3-butadienyl]benzothiazole 2-p-diethylaminostyryl-B-naphthothiazole (a) s 2-p-dimethylaminostyrylB-naphthothiaaole H CH=CH N N C H3 2-p-dirnethylaminostyrylquinollne 8 S e 02H! C-C H=CH -N\ 02115 2-p-diethylaminostyrylbenzoselenazole (9) \N/ CH=CH-CHs Z-styrylquinoline v N -CH=CH 2-o-aminostyry1quino1ine C H: -on=o HQ-N \C Ha 4-p-dimethylaminostyrylquinoline /C H: GH=GH N C Hz 2-13-dimethylaminostyrylpyridine 4-methyl-2-p-diethylnminostyrylthiazole --c n=o n-0 H Z-p-hydroxystyrylquinoline (15) s O Ha 2-p-dimethylaminos tyrylperinaphtho-l,3-thiaziue /CH3 on:

2-p-dimethylaminostyryl-a-n aphthothiazole COH=C HOHa 2-styrylbenzimidazole According to my invention, I incorporate one or more of the dicarbocyanine dyes represented by Formula I represented by Formulas II or III above. My invention is particularly directed to the ordinarily employed gelatino-silver-halide emulsions. However, my super.- sensitizing combinations can be employed in silver halide emulsions in which the carrier is other than gelatin, e. 'g., a resinous substance or cellulosic material which has no deteriorating efiect on the light-sensitive materials. The dicarbocyanine dyes and styryl-type bases can be em ployed in various concentrations depending upon the effects desired.

Ordinarily, the optimum or near optimum concentration of the dicarbocyanine dyes which I employ in practicing my invention isof the order of from 0.616 to 0.30 g. per mol. of silver halide in the emulsion.

The styryI-type bases which I employ in my invention can advantageously be employed at a concentration of from about 0.010 to'1.0 g. per mol. of silver halide in the emulsion.

In general, the ratio of concentration of dicarbocyanine dye to styryl-type base can vary rather widely in my combination, e. g. from 1:1 to 1:100 (by weight) inmany cases.

The methods of incorporating sensitizing dyes and styryl-type bases in silver halide emulsions are well known to those skilled in the art. While the dicarbocyanine dyes and styryl-type bases can be directly dispersed in the emulsions, it is convenient to add the same in the form of solutions in appropriate solvents. Methanol, ethanol, pyridine, and the like have proven satisfactory for many of the dyes of Formula I and bases of Formulas Hand III. Mixtures ofsolvents, e. g., pyridine diluted with methanol or acetone, can also be used. The dicarbocyanine dyes and styryl-type bases are dispersed in the finished emulsions and should be uniformly distributed throughout the emulsions. The following procedure is N-methyl-p-aminophenol sulfate g 2.0 Hydroquinone e g 8.0 Sodium sulfite (desiccated) g 90.0 Sodium carbonate (monohydrate) g 52.5 Potassium bromide g. 5.0 Water to make liter 1 The speed (red), gamma and fog for each of the coatings was then measured. The results are recorded in Table I.

TABLE I Red Light Exposure Example sensitizing Dye and Base (g./mol. AgX

/E- Gamma Fog Speed 1 {(a) 3,3-diethyl0xathiadicarbocyanine iodide (.045) .06

(b dye (a) (.045)withbase1 .15).. 2 dy (.04 .08

(d) dye (a) (045) with base 2 15) .06 3 (e)'dye (a) (.045; with base 3 (.15) 06 4 (f) ye (a) (.045 with base 4 (15) 5 (p) dye (a) (045) with base 5 (1')) 6 dye (a) (.045) with base 6 (.15) 7 (t) dye 045) dye (a) .045) with base? (.15). 8 {(k) 3,3-dlethylthiadiearbocyantne 10 d (Z) dye (k) (.045) with base 2 (.15)

(u) dye (a) (.050) w dye (a) (.050)

w) dye (a) (.050)

(m) 3,3-diethylselenadicarbogyza gneiddide(i045) a's' an; I 11.. base 9 (.08) with base 10 (.08)..

sass-tine" iiiiil' 1:645:11: (.15)

satisfactory: Stock solutions of the dicarbocyanine dyes and styryl-type bases are prepared by dissolving the same in appropriate solvents as described above. Then, to the flowable gelatino-silver-halide emulsion, the desired amounts of the stock solution of one of the dyes (or styryl-type bases) are slowly added, while stirring the emulsion. Stirring is continued until the dye is thoroughly incorporated in the emulsion. Then the desired amount 0t the stock solution of the styryl-type base (or dye, if

styryl-type base has been added first) is slowly added to the emulsion, while stirring. Stirring is continued until the second solution is thoroughly incorporated. The supersensitized emulsion can then be coatedout on a suitable support, such as glass, cellulose derivative film, resin film, or paper, to a suitable thickness and allowed to dry. The details of such coating methods are well known to those skilled in the art. The foregoing procedures and proportions are to be regarded only as illustrative. Clearly, my invention is directed to any silver halide emulsion containing a combination of the aforesaid di-carbocyanine dyes and styryl-type bases whereby a supersensitizing effect is obtained.

The following examples will serve to illustrate further the manner of practicing my invention.

In Table I below, to diiferent portions of the same batch of photographic gelatino-silver-bromiodide emulsion were added (1) a dicarbocyanine dye, such as those rep- In the above table, the coatings of Examples 2, 3, 4, 5 and 6 were made from the same batch of emulsion and thecoatings of Examples 12 to 21 were made from the same batch of emulsion. No measurements of coatings containing only the styryl-type bases alone are'given, since numerous coatings at the concentrations'u's'ed in the table have shown that these bases alone have little or no measurable sensitizing effect on the emulsions.

My invention is primarily directed tothe ordinarily employed gelatino-silver-halide developing-out emulsions, e. g., gelatino-silver-chloride, -chlorobromide, -chloroio dide, '-chlorobromiodide, -bromide and -bromiodide de-' veloping-out emulsions. Emulsions which form the latent image mostly inside the silver halide grains, such as the emulsions set forth in U. S. Patent 2,456,956, dated December 21, 1948, can also be employed in practicing my invention.

The emulsions prepared in accordance with my inven- 7 auric trichloride, etc.) (See U. S. Patents 2,540,085; 2,597,856 and 2,597,915), various palladium compounds, such as palladium chloride (U. S. 2,540,086), potassium chloropalladate (U. S. 2,598,079), etc., or mixtures of such sensitizers; antifoggants, such as ammonium chloroplatinate (U. S. 2,566,245), ammonium chloroplatinite (U. S. 2,566,263), benzotriazole, nitrobenzimidazole, nitroindazole, benzidine, mercaptans, etc. (see Mees- The Theory of the Photographic Proccss, Macmillan P-ub., 1942, page 460), or mixtures thereof; hardeners, such as formaldehyde (U. S. 1,763,533), chrome alum (U. S. 1,763,533), glyoxal (U. 8. 1,870,354), dibromacrolein (Br. 406,750), ete.; color couplers, such as those described in U. S. Patent 2,423,730, Spence and Carroll U. S. Patent 2,640,776, etc.; or mixtures of such addenda.

--Dispersing agents for color couplers, such as those set forth in U. S. Patents 2,322,027 and 2,304,940, can also be employed in the above-described emulsions.

As noted above, methods for preparing the styryl-type bases of my invention represented by Formulas II and III above have been previously described in the prior art. The following example will illustrate the preparation of the compounds of Formula II wherein L represents a nitrogen atom.

Example A.2-p-diethylaminobenzalamirwbenzothiazole An intimate mixture of 1.5 g. (1. mol.) of 2-aminobenzothiazole and 1.8 g. 1. mol.) of p-diethylaminobenzaldehyde was heated, with stirring, in a test tube over a free flame for three minutes. The deep orange sticky mass was dissolved in 2 ml. of methyl alcohol, the solution was stirred with ml. of ether and the whole chilled for one hour in a freezing mixture of ice and acetone. The crystals were collected on a filter and washed with ether. The yield of dye was crude, 8% after four recrystallizations from ligroin (B. P. 6675 C.) and 3% after a further recrystallization from aqueous alcohol.

The orange crystals melted at 95-96" C. with decomposi tion.

Listed below are a number of compounds, together with I literature references describing the preparation thereof.

styryl-type Base Reference Beilsteln, vol. 20, page 497. Chemical Abstracts, vol. 32, pg. 169. Beilstein, vol. 21, page 149.

Jour. Chem. 800., 1943, page 491. Beilsteln, vol. 27, page 385. Chemical Abstracts, vol. 31, pg. 400.

Listed below are melting points for a number of the styryl-type bases of my invention which were prepared exactly according to the methods described in the above prior art references.

styryl-type Base Melting Point 130-132 G. with dec.

60-62" 0. with previous shrinking.

dicarbocyanine dyes of my invention, these styryl dyes do not generally provide the consistent results illustrated in the above examples with respect to the styryl-type bases. It has been found, for example, that the styryl dye, 2-pdimethylaminostyrylbenzoxazole ethiodide, can be employed in supersensitizing combination with various dicarbocyanine dyes, such as dye a of Table I.

The accompanying drawing illustrates the supersensitizing effect obtained with three of my new combinations of dyes in gelatino-silver-bromiodide emulsions. Each figure in the drawing is a digrammatic reproduction of three spectrograms. In each figure, the sensitivity of the emulsion containing only the dicarbocyanine dye of Formula I is represented by the solid curve, the sensitivity of the same emulsion containing only the styryl-type .base of Formula II or III is represented by the curve consisting of dotted lines, while the sensitivity of the same emulsion containing both the dicarbocyanine dye of Formula I and the styryl-type base of Formula II or III is represented by the curve consisting of alternating long and short lines. It will be noted that the maximum sensitizing action for the styryl-type bases generally occurs in the green light region of the spectrum, hence, emulsions containing these styryl-type bases generally show little or no speed to red light, as can be seen by reference to Table I above.

In Fig. 1, curve A represents the sensitivity of an ordinary gelatino-silver-brorniodide emulsion sensitized with 3,3'-diethyloxathiadicarbocyanine iodide, curve B represents the sensitivity of the same emulsion sensitized with 2-p-diethylaminobenzalaminobenzothiazole, while curve C represents the sensitivity of the same emulsion sensitized I p-diethylaminostyrylbenzothiazole.

with both 3,3'-diethyloxathiadicarbocyanine iodide and 2-p-diethylaminobenzalaminobenzothiazole.

In Fig. 2, curve A represents the sensitvity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 3,3'-diethyloxathiadicarbocyanine iodide, curve D repre sents the sensitivity of the same emulsion sensitized with 1 2-p-diethylaminostyrylbenzothiazole, while curve E represents the sensitivity of the same emulsion sensitized with both 3,3'-diethyloxathiadicarbocyanine iodide and 2- Sensitometric measurements for emulsions sensitized in the manner shown in Fig. 2 are given in Example 8 of the above table.

In Fig. 3, curve a represents the sensitivity of an ordinary gelatino-sllver-bromiodide emulsion sensitized with 3,3-diethyloxathiadicarbocyanine iodide, curve F represents the sensitivity of the same emulsion sensitized with 2-[4-( pdimethylaminophenyl) LEI-butadienyl] benzothiazole, while curve G represents the sensitivity of the same emulsion sensitized with 3,3-diethyloxathiadicarbocyanine iodide and 2-4-(p-dirnethylarninophenyl)-1,3- butadienyl] benzothiazole.

What I claim as my invention and desire secured by Letters Patent of the United States is:

l. A photographic silver halide emulsion sensitized with a supersensitizing combination of at least one dicarbocyanine dye selected from those represented .by the following general formula:

wherein R and R each represents an alkyl group, n represents a positive integer of from 1 to 2, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the bcnzothiazole series, those of the naphthothiazo-le series, those of the benzoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the Z-quinoline series, those of the 4-quinoline series, and those of the benzimidazole series, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzoxazole series, those of the naphthoxazole, those of the hemselenazole series, those of the naphthoselenazole series, those of the benzothiazole series, and those of the naphthothiazole series, and at least one heterocyclic base selected from the group consisting of those represented by the following two general formulas:

and

wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the benzoselenazole series, those of the perinaphtho-1,3-thiazine series, those of the benzimidazole series, those of the 2- qninoline series, those of the 4-quinoline series, and those of the Z-pyridine series, L represents a member selected from the group consisting of a nitrogen atom and a methine group. R represents an aryl group, and n represents a positive integer of from 1 to 2.

2. A photographic gelatino-silver-halide developing-out emulsion sensitized with a supersensitizing combination of methine group. R represents an aryl group, and n represented by the following general formula:

N-Rr 1';

wherein R and R each represents an alkyl group containing from 1 to 2 carbon atoms, n represents a positive integer of from 1 to 2, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the Z-quinoline series, those of the 4-quinoline series, and those of the benzimidazole series, and Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzoxazole series, those of the naphthoxazole series, those of the benzoselenaz-ole series, those of the naphthoselenazole series, those of the benzothiazole series, and those of the naphthothiazole series, and at least one heterocyclic base selected from the group consisting of those represented by the following two general formulas:

and

N =0H-0H).. 1 ocrr=oH-ot=oHR2 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the benzoselenazole series, those of the perinaphtho-1,3-thiazine series, those of the benzimidazole series, those of the Z-quin'oline series, those of the 4-quin'oline series, and those of the 2- pyridine series, L represents a member selected from the group consisting of a nitrogen atom and a methine group, R represents a monocyclic aryl group of the benzene series, and n represents a positive integer of from 1 to 2.

3. A photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing combine tion of at least one'dicarbocyanine dye selected from those represented by the following general formula:

iT-Rr it wherein R and R each represents an alkyl group containing from 1 to 2 carbon atoms, n represents a positive integer of from 1 to 2, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the Z-quinoline series, those of the 4-quinoline series, and those of the benzimidazole series, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzoxazole series, those of the naphthoxazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzothiazol series, and those of the naphthothiazole series, and at least one heterocyclic base selected fromthose represented by the following general formula:

A pyridine series, L represents a member selected from the group consisting of anitrogen atom and a methine group, R represents a monocyclic aryl group of the benzene series, and n represents a positive integer of from 1 to 2.

4. A photographic gelatinosilver-halide developingout emulsion sensitized with a supersensitizing combination of at least one dicarbocyanine dye selected from those represented by the following general formula:

wherein R and R each represents an alkyl group containing from 1 to 2 carbon atoms, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzoxazole series, and at' least one heterocyclic base selected from those represented by the following general formula:

I A I It b-L=0HRZ wherein Z represents the non-metallic atoms necessary to complete aheterocyclic nucleus selected from-the group consisting of those of the thiazole series, those of the henzothiazole series, those of the naphthothiazole series, those of the 'benzoXazole-series, those of the benzoselenazole series, those of the perinaphtho-l,3-thiazine series, those of the benzimidazole series, those of the 2-quinoline series, and those of the 2-pyridine series, L represents a member selected from the group consisting of a nitrogen atom and a methinegroup, :and R represents a monocyclic aryl group of the benzene series.

5. -A photographic ,gelatino-silver-halide developing-out emulsion sensitized with a supersensitizing combination of 1 1 at least one dicarbocyanine dye selected from those resented by the following general formula:

rep-

it b-on=on-R,

I 12-16 o=cn-on=on-on=oniii-R1 wherein R and R each represents an alkyl group containing from 1 to 2 carbon atoms, X represents an acid radical, and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzethiazole series, and at least one heterocyclic base selected from those represented by the following general formula:

wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the henzoselenazole series, those of the perinaphtho-l,3-thiazine series, those of the benzimidazole series, those of the 2- quinoline series, and those of the 2-pyricline series, L represents a member selected from the group consisting of a nitrogen atom and a methine group, and R represents a monocyclic aryl group of the benzene series.

8. A photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing combination of at least one dicarbocyanine dye selected from those represented by the following general formula:

EIl -RI X wherein Z, represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, and R represents a monocyclic aryl group of the benzene series.

9. A photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing combination of 3,3'-diethylthiadicarbocyanine iodide and 2-p-diethylaminostyrylbenzothiazole.

10. A photographic gelatino-silver-halide developingont emulsion sensitized with a supersensitizing combination of at least one dicarbocyanine dye selected from those represented by the following general formula:

wherein R and R each represents an alkyl group containing from 1 to 2 carbon atoms, X represents an acid radical, and 2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzoxazole series, and at least one heterocyclic base selected from those represented by the following general formula:

not

o-L=on-m wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole seires, those of the benzoxazole series, those of the benzoselenazole series, those of the perinaphtho-l,3-thiazine series, those of the benzimidazole series, those of the 2- 'quinoline series, and those of the Z-pyridine series, 1., represents a member selected from the group consisting of a nitrogen atom and a methine group, and R represents a monocyclic aryl group of the benzene series.

lLA photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing combination of at least one dicarbocyanine dye selected from those represented by the following general formula:

wherein R and R each represents an alkyl group containing from 1 to 2 carbon atoms, X represents an acid radical, and Z represents the non-metallic atoms neces sary to complete a heterocyclic nucleus of the benzoxazole series, and at least one heterocyclic base selected from those represented by the following general formula;

bl---i)-CI-I=OHR1 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, and R represents a monocyclic aryl group of the benzene series.

12. A photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing combination of 3,3-diethyloxadicarbocyanine bromide and 2-pdiethylaminostyrylbenzothiazole.

13. A photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing combination of at least one dicarbocyanine dye selected from those represented by the following general formula:

13 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and R represents a monocyclic aryl group of the benzene series.

14. A photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing combination of 3,3'-diethyloxathiadicarbocyanine iodide and 2-pdimethylaminostyryl-a-naphthothiazole.

15. A photographic gelatino-silver-halide developingout emulsion sensitized with a supersensitizing coinbination of at least 0 ae dicarbocyanine dye selected from those represented by the following general formula:

wherein R and R each represents an alkyl group containing from 1 to 2 carbon atoms, Xrepresents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzoxazole series,

and at least one heterocyclic base selected from those represented by the following general formula:

N b-0H=0H-R2 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzirnidazole series, and R represents a monocyclic aryl group of the benzene series.

16. A photographic gelatino-silver-halide developingout emulsion sensitized. with a supersensitizing combination of 3,3'-diethyloxathiadicarbocyanine iodide and 2- styrylbenzimidazole.

References Cited in the file of this patent UNITED STATES PATENTS 2,075,046 Mees Mar. 30, 1937 2,313,922 Carroll et al. Mar. 16, 1943 2,448,858 Carroll et al. Sept. 7, 1948 2,680,686 Van Dormael et a1 June 8, 1954 FOREIGN PATENTS 110,697 Australia May 24, 1940 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,852,385 September 16, 1958 Jean E. Jones It is herebj certified that error appears in the printed specification of the above number d t a pa ent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 32, for "trimethylenebenizimidazole" read trimethylene= benzimidazole column 8, line 45, for "In Fig. 3, curve a" read In Fig. 3, curve A column 9, line 29, for 'methine grou R represents an aryl group, and n" read at least one dicarbocyanine dye selected from those column 12, line 26, for "seires" read series Signed and sealed this 30th day of December 1958a gSEAL) ttest:

KARL H 9 AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION SENSITIZED WITH A SUPERENSITIZING COMBINATION OF AT LEAST ONE DICARBOCYANINE DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 